222 I)i'- W. Weltner: Bericht über die Leistungen 



defined from the choanosome. The mesoderm is a dense collen- 

 chyma, containing numerons large granulär cells in addition to 

 collencytes. The chamber-system is diplodal. 

 Gen. Thrombus SoUas. 

 Order II: Lithistida O. Schm. 



Tetractinellida provided with a consistent skeleton by the zygosis 

 of modified spicules or desmas. 

 Suborder I: Hoplophora. 



Lithistida provided with special ectosonial spicules, and 

 usually with sorae form of microsclere. 

 Demus I ; Triaenosa. 



Hoplophora in which the ectosomal spicules are sonie form 

 of triaene, and in which microscleres (spirasters. amphi- 

 asters, or microrabds) are invariably preseut. The chamber- 

 system is aphodal. 

 Farn. Tetracladidae (Zittel). 



Triaenosa in which the desma is tetracrepid. 

 Gen. Theonella Gray, Discodermia ßocage, Rhacodiscula Zittel, 

 Kaliapsis Bwk., Neosiphonia Sollas, Rimella 0. Schm., 

 Collinella 0. Schm., Sulcastrella 0. Schm. 

 Fam. Corallistidae Sollas. 



Triaenosa in which the desma is monocrepid and tuberculate. 

 Chamber-system aphodal. 

 Gen. Corallistes 0. Schm., Macandre wia Gray, Daedalopelta 

 Sollas, Heterophymia Pomel, Callipelta Sollas. 

 Fam. Pleromidae Sollas. 



Triaenosa in which the desma is monocrepid and smooth, not 

 tuberculated ; zygosis occurs between the ends of the cladi 

 of one desma and the epirabd of another. Chamber-system 

 aphodal. 

 Gen. Pleroma Sollas, Lyidium 0. Schm. 

 Demus II: Rhabdosa. 



Hoplophora in which the ectosomal spicules are microstron- 

 gyles, or modified microstrongyles (discs). The desmas 

 are monocrepid. 

 Fam. Neopeltidae Sollas. 



Rhabdosa in which the ectosomal spicules are monocrepid 

 discs. 

 Gen. Neopelta 0. Schm. 

 Fam. Scleritodermidae Sollas. 



Rhabdosa in which the ectosomal spicules are microstrongyles, 

 and the other microscleres sigmaspires. 

 Gen. Scleritoderma 0. Schm., Aciculites O. Schm. 

 Fam. Cladopeltidae Sollas. 



Rhabdosa in which the ectosomal spicule is a monocrepid 

 desma highly branched in a plane parallel to the surface. 

 Microscleres are absent. 

 Gen. Siphonidium 0. Schm. 



